1. Field of the Invention
The present invention relates to an image processing system for electrically processing image data.
2. Description of the Prior Art
A so-called digital copying machine has become commercially available. In this copying machine, an original document is very precisely read by an image sensor such as a CCD, and the read signals are digitized and subjected to image enlargement/reduction processing and editing processing. Resultant digital signals are used to form an image by a printer such as a laser beam printer (LBP) or the like.
In a digital copying machine of this type, an expensive large-capacity page memory for storing image data is not used in order to obtain a low-cost construction and a high-speed operation. Instead, this digital copying machine has a small circuit size but processes digital signals at high speed. However, in order to obtain a facsimile system by using such a digital copying machine, it is very difficult to technically perform compression and expansion of digital data in units of lines in real time since the digital signals are processed at a very high speed, resulting in inconvenience.
In order to overcome this drawback, the digital signal is processed at low speed to decrease a scanning rate or recording speed of the original document. Alternatively, in the same manner as a conventional facsimile system, the original document is intermittently read to perform image forming operation which must then be matched with data compression/expansion.
In this case, the image forming apparatus must perform a different reading or recording operation depending upon whether it is used as a digital copying apparatus or as a facsimile system, resulting in a complex arrangement and high cost. This is contrary to the purpose described above.
It is therefore desired that a high-speed digital copying machine be usable without modification so as to perform as part of a facsimile system.
An arrangement having a bus for transmitting image data in addition to a bus for transmitting control data for controlling the operation of an image reading section and an image recording section results in high cost and a complicated configuration. However, when the image data is transmitted through the control bus, the bus is occupied by the image data for a long period of time, and normal control data will not be properly transmitted. In addition to this disadvantage, the image reading/recording rate confined within the limit of a processing speed of a computer bus or another block connected thereto.